Soap is created when fats or oils (fatty acids) are mixed with an alkali (metal), such as lye. A chemical reaction called saponification occurs and soap is the resulting product. A soap cleaning capacity is affected by hard water.
How is it different than a detergent?
Detergents use a synthetic (man-made) surfactant in place of the metal/fatty acid salt that is used in soap. Detergents react less to minerals in hard water. Most detergents are made with petroleum-based materials but there are may new detergents being made with renewable materials.
Then, what is a surfactant?
All soaps and detergents contain a surfactant (surface active agents) as their active ingredient. The head of the surfactant acts a a wetting agent, lowering the surface tension and allowing penetration of water molecules. The tails forms an emulsion with any oily particles and encapsulates dirt particles, allowing them to be washed away.
You will sometimes see the term "surfactant&quo…